Duncan arrived in Dallas Sept. 20 from Liberia and fell ill a few days later. He was sent home after an initial visit to the emergency room, but taken back to the hospital Sept. 28 and has been kept in isolation ever since.

Others in Dallas could be in danger as officials try to contain the virus that has ravaged West Africa, killing thousands of people. Officials say 10 people had direct contact with Duncan while he was contagious.